Retina
Fiona Rowe in Visual Fields via the Visual Pathway, 2016
The retina is divided by the outer plexiform layer so that the inner half receives its blood supply from the central retinal artery and the outer half closest to the choroid is supplied by the choroid capillaries derived from the ciliary vasculature. The central retinal artery is a branch of the ophthalmic artery and enters the eyeball with the optic nerve where it divides into two equal superior and inferior branches which in turn divide into superior and inferior nasal and temporal branches. The resulting four branches each supply a quadrant of the retina. There is no overlap of these blood vessels and no anastomosis between branches within each retinal quadrant. The fovea is supplied by an anastomosis of the central retinal artery and the choroidal circulation. The central retinal vein is formed by the union of tributaries that correspond approximately to the branches of the central artery. It leaves the eye within the optic nerve.
Answers
Andrew Schofield, Paul Schofield in The Complete SAQ Study Guide, 2019
Central retinal artery occlusion is one of the differential diagnoses of sudden painless loss of vision. With this particular clinical problem, a general examination should be performed as well as taking a good past medical history in order to find a root cause. The commonest cause is a thromboembolic event, hence the need for a brief cardiovascular examination. On examination of the eyes, the afferent pupillary defect will be the first noticeable sign (this is seen as an absence of pupillary constriction when a light is shone into the affected eye, whilst there will be pupillary constriction in the affected eye if light is shone into the non-affected eye). The retina will appear pale due to ischaemia, but a cherry-red spot will be evident at the macula due to blood supply coming from the underlying choroid. If central retinal vein occlusion is due to an inflammatory process, such as temporal arteritis (as in the clinical case described), then high-dose steroids are required as soon as possible, as there is only a 6-hour window in which to save the patient’s sight.
Fabry disease
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop in Atlas of Inherited Metabolic Diseases, 2020
Ocular lesions [22] regularly include dilated tortuous venules of the conjunctivae (Figure 87.5). Similar dilatation may be seen in the vessel of the retinas. Corneal opacities develop in males and in some heterozygous females. The diagnosis can be made by slit lamp examination, in which the typical cream-colored interior, whorl-like opacities are visualized. Corneal opacities have been seen as early as six months of age [23]. Cataracts of the posterior capsule of the lens are pathognomonic [22]. The ocular lesions result from the deposition of glycosphingolipid and do not usually impair vision. As the disease progresses, the retinal changes of uremia may be found. Visual loss has been observed following central retinal artery occlusion [24]. Some patients display edema of the eyelids, in the absence of renal disease [22, 23]. The ocular manifestations of disease, especially cornea verticillata correlated with severe disease in pediatric patients [25]. Neurosensory hearing loss may develop [18].
Impact of visual impairment following stroke (IVIS study): a prospective clinical profile of central and peripheral visual deficits, eye movement abnormalities and visual perceptual deficits
Published in Disability and Rehabilitation, 2022
Fiona J. Rowe, Lauren R. Hepworth, Claire Howard, Kerry L. Hanna, Jim Currie
Visual acuity is a primary measure of central visual function. The majority (81.4%) of stroke survivors needed glasses and wore their current glasses for visual acuity assessments. The mean near and distance visual acuities were below cut-off levels of low vision defined by the World Health Authority [20] and, by default, below levels acceptable for driving according to international driving regulations [21,28]. Our findings are similar to other studies reporting reduced central vision with reports of 15–25% at logMAR levels worse than 0.5 [29,30]. New onset reduced central vision may be due to stroke-related impact to the visual pathway. Arterial blood supply to the retina is from the central retinal artery – a branch from the anterior cerebral artery. Healthy vascular perfusion of the retina, and particularly the foveal and macular areas, is essential to high level central vision [2]. It is feasible that reduced central vision following stroke may reflect reduced perfusion and relative ischaemia within the anterior visual pathway. Visual field loss was predominantly homonymous hemianopia and quadrantanopia as is frequently reported [31–34].
Giant cell arteritis
Published in Postgraduate Medicine, 2023
The most serious complication of GCA remains permanent visual loss which can occur in up to 20% of patients before glucocorticoid therapy initiation [66]. In a study of patients with biopsy-proven GCA, patients with ocular involvement were older, with a lower ESR and were less likely to have a headache or other systemic symptoms of giant cell arteritis than those without ocular involvement [67]. Two proposed reason for this variability in ocular involvement are the lack of classic symptoms of GCA making patients less likely to be referred for temporal artery biopsy and treatment in a prompt fashion and that those with a highly inflammatory response (elevated inflammatory indices) had more circulating IL-6 which has angiogenic properties and could counteract the arteritic ischemia of GCA [66]. GCA has a predilection for the ophthalmic artery and its branches most importantly the posterior ciliary arteries and the central retinal artery. The posterior ciliary arteries perfuse the choroid which nourishes the photoreceptors in the outer third of the retina and the optic nerve head. The central retinal artery provides blood to the inner two third of the retina including the retinal ganglion cells – the axons forming the optic nerve. The ophthalmic artery in addition to these two branches, also provides blood to the extraocular muscles and the vasa nervorum of the ocular motor nerves [68]. Vision changes in GCA have been described as a result of each of these vessels, in addition, vessels in the vertebrobasilar circulation can become involved which supplies circulation to the occipital lobe.
Diffusion-Weighted Magnetic Resonance Imaging in Acute Retinal Pathology
Published in Neuro-Ophthalmology, 2018
Omar Alsinaidi, Aasef G. Shaikh
A 57-year-old woman with history of hypertension presented with acute painless vision loss from the left eye. She reported intermittent symptoms of flashing lights and blurred vision in her left eye for 2 days prior to presentation. Subsequently, her vision acutely turned grey and then black, when she presented to the emergency room. Examination revealed light perception in the left eye, and arteriolar narrowing with boxcarring and a pale fundus. Table 1 depicts the details of pertinent ophthalmological examination. Remaining neurological examination was unremarkable. The findings were consistent with central retinal artery occlusion. DWI sequence revealed multiple areas of diffusion restriction in the left retina (Figure 1A) suggestive of multiple punctate infarcts. There were no significant vascular stenoses, as confirmed in intracranial and neck magnetic resonance angiograms (MRAs). Echocardiogram revealed a mobile mass measuring 1.28 × 0.88 cm on the posterior mitral annulus. The mass was removed surgically, and pathology showed fibrin and calcification consistent with vegetation. Microorganisms were not found, as the patient was on empiric broad-spectrum intravenous antibiotics.